Dilatation and evacuation: Cervical Preparation

Last reviewed: November 18, 2022

Recommendation:

• Routine preoperative cervical preparation is recommended before dilatation and evacuation (D&E).
• Osmotic dilators, misoprostol and mifepristone are options for cervical preparation. The choice depends on availability, expense, gestational age and timing of the procedure.

Strength of recommendation: Strong

Quality of evidence: High

Background

Cervical preparation prior to D&E reduces the risk of procedure-related complications (Fox & Krajewski, 2014; Peterson et al., 1983). There is limited data to suggest the best method of cervical preparation before D&E because the trials that exist have heterogeneous comparisons, proxy outcomes for adverse events, small sample sizes, and include few individuals with pregnancies over 20 weeks (Ralph & Shulman, 2019). Available trials typically show differences in cervical dilation or procedure times, however they do not include enough participants  to show differences in rare but more serious outcomes such as cervical or uterine injuries or inability to complete the procedure (O’Shea et al., 2021). Choice of method of cervical preparation is often limited by supply availability, especially in low-resource settings.

Osmotic dilators

Osmotic dilators are safe, effective and do not increase infectious morbidity (Bryman, Granberg, & Norström, 1988; Fox & Krajewski, 2014; Jonasson et al., 1989; Peterson et al., 1983). A 2021 systemic review and meta-analysis of cervical preparation before D&E between 14-24 weeks gestation showed that cervical priming regimens that included osmotic dilators provided better cervical dilation and reduced procedure difficulty when compared to regimens that did not include dilators; but dilator regimens were also associated with decreased patient satisfaction  (O’Shea et al., 2021). In one randomized controlled trial, synthetic dilators placed on the day of D&E resulted in less initial cervical dilation and required more mechanical dilation than overnight laminaria although there were no differences in procedure duration or complications between the two groups (Newmann et al., 2014). Decisions about the number and timing of dilators to place should be individualized and take into consideration the type of dilator and its size, the gestational age of the pregnancy, parity and cervical compliance, and the provider’s experience (Fox & Krajewski, 2014; Diedrich, Drey, & Newmann, 2020).

People experience pain both during dilator placement and overnight as dilators expand in the cervix; pain typically peaks two hours after dilator placement (Creinin et al., 2020; Liu & Flink-Bochacki, 2020; Nagendra et al., 2020) and does not differ by type of dilator used (Liu & Flink-Bochacki, 2020). In randomized controlled trials, provider-administration of paracervical block (Shaw et al., 2021; Soon et al., 2017) or self-administration of 2% lidocaine gel (Schivone et al., 2019) prior to osmotic dilator insertion eases the discomfort of dilator placement and use of non-steroidal anti-inflammatory medications (NSAIDs) decreases the experience of cramping pain for the hours following insertion until procedure, compared to oral opioids (Nagendra et al., 2020).

Misoprostol

Misoprostol is inexpensive, safe (Nucatola et al., 2008), and more readily available than osmotic dilators in many low-resource settings. Misoprostol may be used alone for cervical preparation prior to D&E up to 20 weeks gestation (Fox & Krajewski, 2014; O’Connell et al., 2008; Shakir-Reese et al., 2019); there is limited data to support use of misoprostol as a single agent after 18 weeks (Maurer, Jacobson, & Turok, 2013; Shakir-Reese et al., 2019). In studies comparing osmotic dilators to misoprostol, dilators provided more cervical dilation (Goldberg et al., 2005; Sagiv et al., 2015; Shakir-Reese et al., 2019). However, those who received misoprostol for cervical preparation were able to have their procedures safely completed on the same day (Bartz et al., 2013; Goldberg et al., 2005; Sagiv et al., 2015), and patients often preferred misoprostol to dilators (Goldberg et al., 2005). Misoprostol may be given to individuals with a prior cesarean delivery, as uterine rupture is rare (Fox & Krajewski, 2014). A study of same-day use of osmotic dilators plus adjunctive 400mcg misoprostol versus only misoprostol 4-6 hours prior to D&E up to 20 weeks gestation resulted in comparable D&E procedure times between the two groups, although the osmotic dilator plus misoprostol group had significantly greater dilation at D&E initiation (Shakir-Reese et al., 2019). Because placing osmotic dilators takes more time than was saved by having greater baseline dilation, the overall procedure time (placing osmotic dilators plus D&E procedure) was longer by 3.2 minutes in the osmotic dilator plus misoprostol group. The Royal College of Obstetricians and Gynaecologists and the Society of Family Planning recommend against adjuvant misoprostol for patients who received uncomplicated dilator insertions the day prior to D&E (Diedrich, Drey, & Newmann, 2020; O’Shea et al., 2021), while the World Health Organization (WHO) recommends adding an adjuvant medication (misoprostol, mifepristone, or both) to osmotic dilators for D&E at or after 19 weeks (WHO, 2022).

Misoprostol plus osmotic dilators

A meta-analysis of three randomized controlled trials of misoprostol versus placebo added to overnight laminaria at gestational ages greater than 16 weeks found that adjuvant misoprostol did not significantly decrease procedure time or the need for initial dilation found that adjuvant misoprostol did not significantly decrease procedure time or the need for initial dilation  (Cahill et al., 2019). Overall complication rates were low in all three studies and did not differ significantly by treatment group , however in all studies side effects were greater among those using misoprostol (Cahill et al., 2019: Drey et al., 2013; Edelman et al., 2006; Goldberg et al., 2015). The Royal College of Obstetricians and Gynaecologists and the Society of Family Planning recommend against adjuvant misoprostol for patients who received uncomplicated dilator insertions the day prior to D&E (Diedrich, Drey, & Newmann, 2020; O’Shea et al., 2021), while the World Health Organization (WHO) recommends adding an adjuvant medication (misoprostol, mifepristone, or both) to osmotic dilators for D&E at or after 19 weeks (WHO, 2022).

Two small prospective randomized triasl have examined adding misoprostol to dilators for same-day D&E (Borras et al., 2016; Kim et al., 2022). Investigators ended both studies early- one due to difficulty recruiting participants (Kim et al., 2022) and the other due to an unexpectedly high rate of complications, specifically serious cervical lacerations—in participants over 19 weeks gestation who received dilators alone for cervical preparation (Borras et al., 2016).

Mifepristone

One randomized trial of 50 women between 14-16 weeks gestation compared mifepristone as a single agent to dilators, both administered the day prior to the abortion procedure (Borgatta et al., 2012). Study participants who had cervical preparation with osmotic dilators had a slightly shorter procedure time and greater dilation compared to those given mifepristone, but women had less pain with mifepristone and strongly preferred it. A second randomized trial of 49 women between 15-18 weeks gestation with similar design (single-agent mifepristone compared with osmotic dilators placed the day prior to procedure) found no difference in procedure time between the two treatment groups (Paris, et al, 2019). When asked, most participants who received the mifepristone preferred it, while most who received osmotic dilators reported that they would have preferred a different treatment option for cervical priming.

In studies examining the use of mifepristone in combination with misoprostol, same-day administration of mifepristone plus misoprostol is no better than misoprostol alone (Casey et al., 2016), and while administration of mifepristone 2 days prior to misoprostol resulted in improved cervical dilation in one study, the rate of preprocedure fetal expulsions was also increased (Carbonell et al., 2007). When compared to overnight dilators plus misoprostol, mifepristone administered the day prior to the abortion plus same-day misoprostol is less effective (Shaw et al., 2017).

Mifepristone plus osmotic dilators

Two randomized trials have assessed the addition of mifepristone to overnight osmotic dilators plus misoprostol for cervical preparation; neither study showed additional benefit with mifepristone (Shaw et al., 2017; Shaw et al., 2015). A third randomized trial compared overnight dilators alone, overnight dilators plus misoprostol, and overnight dilators plus mifepristone (Goldberg et al., 2015), and found that procedure times were no different between the three groups, although providers reported that procedures between 19-24 weeks gestation were easier in the dilators plus mifepristone group.

Who can perform cervical preparation before D&E?

WHO makes service delivery recommendations for the provision of D&E, which includes assessment of gestational age, cervical preparation, the procedure itself, pain management including the provision of a paracervical block, and the assessment of procedure completeness through visual examination of the products of conception (WHO, 2022). WHO advises that provision of medication for cervical preparation is within the scope of practice of specialty and general medical practitioners; and recommends the provision of cervical preparation medications by associate and advanced associate clinicians, midwives, nurses, auxiliary nurses and auxiliary nurse midwives, and traditional and complementary medicine professionals, based on expected competencies for these roles and low-certainty evidence of safety and effectiveness. Although there is insufficient direct evidence, WHO suggests that community health workers, pharmacists and pharmacy workers can safely and effectively provide medications for cervical preparation based on expected competencies for these roles, adding that these health workers need to ensure continuity of care for the individual obtaining the medications before an abortion procedure (WHO, 2022). WHO advises that cervical preparation with osmotic dilators is within the scope of practice of specialty and general medical practitioners, and recommends the placement of osmotic dilators by associate and advanced associate clinicians, based on indirect evidence and the expected competencies for these health worker roles. Although there is insufficient direct evidence, WHO recommends that midwives, nurses, auxiliary nurses and auxiliary nurse midwives can perform transcervical procedures-including osmotic dilator placement-based on the expected competencies for these roles. For further information about health worker roles in abortion care, see Appendix C: World Health Organization recommendations for health worker roles in abortion care.

References

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